1. Field of the Invention
The present invention relates to an article made by joining two members together, and particularly, to an article containing two members bound to each other with a binding layer formed through a heating step between one of the members made of a metal and the other member made of a material of the same type or a different type as the one member. The present invention also relates to a brazing filler metal for forming that binding layer.
2. Description of the Prior Art
A rotor for a motor is a conventionally known article of this type. In this rotor, one member is a permanent magnet containing a rare earth element, and the other member is a rotor body made of a steel which is a different material than the permanent magnet.
The permanent magnet containing the rare earth element has a nature that the machinability thereof is poor, because the permanent magnet is very brittle, and that if the permanent magnet is exposed to a high temperature, the metallographic structure thereof is changed, and as a result, the magnetic characteristic of the permanent magnet is influenced.
In mounting the permanent magnet to the steel rotor body, a mounting means such as a dovetail structure, a screwing, a welding and the like cannot be employed and hence, an adhesive has conventionally been employed.
However, if an adhesive is used, the following problems are encountered: the strength of bonding between the permanent magnet and the rotor body is low, because of a poor wettability of the permanent magnet, and the bonding strength is significantly reduced with a rise in temperature. In such a situation, it is not possible to meet the demand for an increase in speed of rotation of the motor.